Cycloalkane, cycloalkene, and cycloalkanone phosphonates

ABSTRACT

Compounds are described which are useful as flame retardants for chemical incorporation into polyurethane and like polymer foams and which have the formula:   WHEREIN R1 and R2 are each hydrocarbyl or halohydrocarbyl, CnH2n is alkylene (C2-8) R3 and R4 taken together with the attached C atom are the residue of a cycloalkane, cycloalkene or cycloalkanone. The compounds have two active hydrogen atoms (marked with an asterisk) which show substantially equal reactivity towards isocyanato groups in sharp contrast to closely related compounds hitherto known.

1ited States Patent 1 1 Smith et al.-

[ CYCLOALKANE, CYCLOALKENE, AND

CYCLOALKANONE PHOSPHONATES [75] Inventors: Curtis P. Smith, Cheshire; Henri Ulrich, Northford, both of Conn.

[73] Assignee: The Upjohn Company, Kalamazoo,

Mich.

[22] Filed: Aug. 8, 1973 [21] App]. No; 386,520

Primary Examiner-Lorraine A. Weinberger Assistant Examiner-Richard L. Raymond Attorney, Agent, or Firm-Denis A. Firth; John Kekich 1451 Dec. 17, 1974 5 7 ABSTRACT Compounds are described which are useful as flame retardants for chemical incorporation into polyurethane and like polymer foams and which have the formula:

wherein R and R are each hydrocarbyl or halohydrocarbyl, C I-l is-alkylene (C and R, and R taken together with the attached 0. atom are the resi- 4 due of a cycloalkane, cycloalkene 0r cycloalkanone.

The compounds have two active hydrogen atoms (marked with an asterisk) which show substantially equal reactivity towards isocyanato'groups in sharp contrast to'closely related compounds hitherto known.

3 Claims, N0 Drawings CYCLOALKANE, CYCLOALKENE, AND CYCLOALKANONE PHOSPHONATES BACKGROUND OF THE INVENTION described for use, in particular, in imparting flame retardancy to polyurethane foams by including the phosphorus-containing polyol as part of the polyol component which is to be reacted with polyisocyanate in the preparation of said foam. Such phosphorus-containing polyols become chemically incorporated into the polymer backbone. They are therefore preferred over other phosphorus and/or halogen containing fire retardant additives which contain no active hydrogen atom and which, because of this, cannot become chemically incorporated into the polymer and tend to leach out of the resulting foams over a period of time.

One of the most commonly employed class of phosphorus containing polyols is the class of dialkyl di(hydroxy-alkyl)aminomethaneiphosphonates disclosed in U.S. Pat. No. 3,076,010. These materials are recognized in the art to impart highly significant flame retardant propertiesto polyurethane foams in which they are incorporated. However, they suffer the disadvantage of exhibiting a tendency to impart hydrolytic instability to the polyurethane and also of being relatively unstable when stored in combination with other polyols employed in the preparation of polyurethane foams. It is common practice to supply two component systems for the manufacture of polyurethanes, one component being a polyisocyanate or an isocyanate-terminated prepolymer, and the second component being a mix- 7 ture of the polyols, surfactants, catalysts and like addi- Typical of these compounds is dimethyl N-(2- hydroxyethyl)-2-aminopropyl-Z-phosphonate which has the' following formula:

CH CH The two active hydrogen atoms are indicated by asterisks. Unfortunately, it is found that the active hydrogen atom attached to the nitrogen atom in the above molecule has a muchgreater activity, in reaction with isocyan'ate groups, than does the activehydrogen 'atom of the. hydroxyl group. So much so that reaction between the above compound and isocyanate takes place almost exclusively via the active hydrogen atom attached to nitrogen and little or no reaction occurs at the hydroxyl group. Hence, the phosphorus containing compound of the above formula tends to act as a chain stopper when employed in the preparation of polyurethane foams.

We have now found a related series of compounds which are free from the above problem but which do posess good hydrolytic stability when incorporated in polyurethane foam, and storage stability when stored in combination with other conventional polyols.

DETAILED DESCRIPTION OF THE INVENTION The invention comprises a compound having the formula:

wherein R and R are each selected from the class consisting of hydrocarbyl from I to 12 carbon atoms, inclusive, and halo-substituted hydrocarbyl from 1 to .12 carbon atoms, inclusive; 1

C,,H represents alkylene from 2 to 8 carbon atoms, inclusive, having at least two carbon atoms separating the valencies; and

R and R taken together with the carbon atom to which they are attached, represent the residue of a cyclic member selected from the class consisting of cycloalkane, a cycloalkene, and a cycloalkanone, each of said cycloalkane, cycloalkene and cycloalkanone having from 4 to 8 ring carbon atoms, inclusive. and having from O to 4 lower-alkyl suhstituents.

The invention also comprises polyurethane foams having incorporated therein, as part or the whole of the polyol component used in their preparation, aphosphorus-containing compound of the formula), The term hydrocarbyl'from I to 12 carbon atoms, inclusive," means the moiety obtained by removing one hydrogen atom from a hydrocarbon having the stated carbon atom content. Illustrative of hydrocarbyl are alkyl, such as methyl, ethyl, propyl, hexyl, octyl, decyl, dodecyl and the like; alkenyl such as allyl, methallyl, hexenyl, nonenyl, undecenyl, dodecenyl, and the like; cycloalkyl, such as cyclobutyl, cyclohexyl, cyclooctyl, methylcyclohexyl, dimethylcyclohexyl, and the like; cycloalkenyl such as cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclo'c'ictenyl, methylcycloheptenyl, and the like; aralkyl such as benZyLphenethyI, phenylpropyl, phenylhexyl, naphthylmethyl, and the like; and-aryl such as phenyl, tolyl, xylyl, naphthyl, biphenylyl, and the like.

The term halo-substituted hydrocarbyl from I to 12 carbon atoms, inclusive means hydrocarbyl, as above defined, in which at least one hydrogen atom has been replaced by halo i.e., fluoro, chloro, bromo or iodo.

Said halo-substituted hydrocarbyl moieties can contain butylene, 1,6-hexylene and the like.

Illustrative of cycloalkane having from to 4 loweralkyl substituents are cyclobutane, methylcyclobutane, cyclopentane, methylcyclopentane, ethylcyclopentane, dimethylcyclopentane, cyclohexane, isopropylcyclohexane, cycloheptane, methylcycloheptane, trime- 5 thylcycloheptane, ethyltrimethylcyclohexanc, cycloiictune and the like. Illustrative of cycloalkcne having from to 4 lower-alkyl substituents are cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, methylcyclopentene, trimethylcyclopentene, isol0 bon atoms, inclusive, such as methyl, ethyl, propyl, bu- 2O tyl, pentyl, and hexyl including isomeric forms thereof.

DETAILED DESCRIPTION OF THE INVENTION The compounds of the formula (I) can be prepared using procedures well-recognized in the art. Illustratively, the compounds of the'formula '(I can be prepared by the process showri schematically as follows:

l \1. l 12 0 R3 \R wherein R R R R, and C,,H are as hereinbefore defined. The reaction can be carried out under conditions generally employed in the art as illustrated, for example, by the reaction conditions described in the aforesaid US. Pat. Nos. 3,076,010 and 3,385,914.

Briefly, the reactants are brought together in substantially stoichiometric proportions in the presence of an inert organic solvent ie a solvent which does not enter into, or in any way interfere with, the desired course of the reaction. Illustrative of such solvents are alkanols methylcyl5 such as methanol, ethanol, isopropanol, and the like, ethers such as diethyl ether, dioxane, tetrahydrofurane, and the like, and hydrocarbons such as hexane, heptane, octane, benzene, toluene, cyclohexane and the like. Advantageously, the dihydrocarbylphosphate (III) and the alkanolamine (V) are brought togetherin the inert organic solvent and the ketone (IV) is added to the mixture usually in increments to control the exothermic reaction which takes place. The reaction temperature is advantageously maintained in the range of about 40C to about C by cooling if necessary and- /or by controlling the rate of addition of the ketone (IV). The resulting product (I) is isolated from the reaction mixture by conventional procedures e.g., by evaporation of the solvent and purification of the residue if desired, by distillation under reduced pressure (in the case where the product is a liquid), recrystallization (in the case where the product is a solid) or by otherconventional techniques.

Those compounds of the formula (I) wherein the group C,,H has only two carbon atoms between the valencies i.e. wherein C I-I is ethylene or a loweralkyI-substituted ethylene, can be prepared by an alternative method which is illustrated by the following wherein R R R and R are as hereinbefore defined and A and B represent hydrogen or lower-alkyl. The

40 compound (VI) is the product obtained by condensing the alkanolamine l NH -CHCH-OH 60 and the ketone (IV) in the presence of an inert solvent under the temperature conditions discussed. While we believe that the product so obtained is in the form of -an oxazolidine represented by the formula (VI) above there is some dispute in the literature as to the nature of such products. It has been suggested (Bergmann; et al. J. A. C. S. 75,358,1953) that the product is actually an equilibrium mixture of the oxazolidine (VI) and the corresponding imine or Schiffs base represented by the formula i C N-cH-CH-OH,

the proportion of the two components being determined by the nature of the ketone. It is unnecessary to discuss thisquestion in detail here but we wish to make it clear that, whatever the actual fine details of the structure, the compound (VI) is intended to represent the product of condensation of the ketone (IV) and the alkanolamine I i "nH -cH-cH-on since it is this condensation product, whatever its structure, which is employed in the reaction with the dihydrocarbylphosphite (III) in the alternative synthesis of the compounds (I) of the invention.

The dihydrocarbyl phosphite (III), the ketones (IV) and the alkanolamines (V) are so well-known in theart, as are methods for their preparation, that it is un-- necessary to catalogue such details here.

The novel compounds (I) of the invention are useful in that, whenincorporated into polyurethane foams by methods to be described hereinafter, they impart flame retardance thereto. They have the advantage that they can be. stored for prolonged periods in combination with other polyol components without causing deleterious effects, they do not reduce the hydrolytic stability of polyurethane foams into which they are incorporated and they possess two active hydrogen atoms of approximately equal activity towards isocyanate groups thus ensuring that they become chemically incorpo- ClCHCH c1 ca ergo fated withp ficulty intqt q P yuret an Po y chain. They do not act as chain stoppers when so used. The novel compounds (I) of the invention can be incorporated into polyurethane foams simply by replacing at least a part of the polyol employed in the condensation with polyisocyanate in the preparation of said foam, with compound (I). In order to produce significant flame retardancy, the amount of compound (I) incorporated in the foam is generally such that the resultant foam contains at least 1.0 percent by weight of phosphorus. The methods employed in the art to pre pare polyurethane foams are so well-known as to need no detailed description here: see, for example. Saunders, et al., Polyurethanes, Chemistry and Technology Part II, pp. 1 298, 1964, Interscience, NY.

The following examples describe the manner and process of making and using the invention. and set forth the best mode contemplated by the inveptors of carrying out the invention, but are not to be construed as limiting.

EXAMPLE I Di(2-chloropropyl) hydroxyethyl)aminocyclohexylphosphonate A total of 170.3 g. 1.74 mole) of cyclohexanone was added with stirring to a solution of 109.8 g. 1.80 mole) of monoethanolamine in 300 ml. of benzene. The resulting mixture was heated under reflux and the water of condensation which was eliminated was removed continuously by azeotropic distillation using a Dean- Stark trap. The theoretical amount of water (31.3 ml.)

was removed in 2 hrs. At the end of this period the benzene was removed by distillation under reduced pressure. The residue (244 g.) was a golden colored liquid which can be represented by one of the formulae:

in the form of a clear yellow oil. Anal:

Calcd. for C I-I NO PCl C, 44.7; H, 7.4; N, 3.7; P,

8.2; Cl, 18.8 Found; C, 44.2; H, 7.5; N, 3.6; P, 7.5; Cl, 18.4

EXAMPLE 2 Diethyl l-(2-hydroxyethyl)aminocyclohexylphosphonate Using the procedure described in Example 1, but re- Or =NCH CH OH 7 r 8 placing the di( 2-chloropropyl)phosphite by an equivaiy lent amount of diethyl phosphite, there was obtained ly diethyl 1-(Z-hydroxyethyl)aminocyclohexylphosphonf'(P' P ate having the formula: dt-benzyl, and C H50 0 dlcyclohexyl l-(2-hydroxyethyl)aminocyclohexyla I phosphonate.

NHCH: EXAMPLE 5 Cause A mixture of 74 g. (1 mole) ofisopropanolamine, 138 g. (1 mole) of diethyl phosphite and 200 g. (1.4

mole) of anhydrous sodium sulfate in 200 ml. of benzene was stirred while a total of 98 g. (1 mole) of cyclohexanone was added. The mixture was cooled when in the form of a Clear yellow liquid. necessary to maintain the reaction temperature below Anal: about 50C. After the temperature subsided the mix- Calcd. for CHHZGNOiP; (3,516]; H 932; N, 502; P ture was stirred for a further 2 hours and then filtered. l H l g The filtrate was evaporated to dryness. There was thus Found; C, 5139; H, 964; N 495; P, 1066 obtained diethyl l-(Z-hydroxypropyl)aminocyclohexylphosphonate. 7 EXAMPLE 3 Similarly, using the above procedure, but replacing Using the procedure described in Example 1, but re- 'sopmpanolammc by pmpunolamlnei hexanola' placing the cyclohexanone there used by an equivalent oclamlamlllei z'hydroxyhixylamlne and amount of isophorone (35,5 trimethyl 2 hydroxy-Z-octylamme, there were obtained: cyclohexanone) there was Obtained di(} diethyl l-(3-hydroxypropyl)aminocyclohexylphoschloropropyl) l(Z-hydroxyethyl) amino-3,5,5- phqnate trimethyl-2-cyclohexyl-phosphonate having the fordlethyl 3v'dr0Xyhexyl)ammocyclohexylphosphonate CH Cl 'CH -CH O\fi cu p mica ca on C1-'- CH- CH 0 ca ctr Similarly, using the procedure described in Example 'diethyl l -(Z-hydroxyhexyl)aminocyclohexylphosl, but replacing cyclohexanone by an equivalent phonate, amount of cyclopentanone, 2,2,4,4-tetramethylbuand diethyl l-(4-hydroxy-2-octyl)aminocyclohexylphosphonate, respectively.

tanedione-l,3, 2-cycloheptenone, or cyclooctanone, there was obtained: di(Z-chloropropyl) l-(Z-hydroxyethyl)aminocyclopentylphosphonate,

di(2-chloropropyl) l-(2-hydroxyethyl)amino-2,2,4,4- tetramethylcyclobutan-3-onylphosphonate di(Z-chloropropyl) l-(2-hydroxyethyl)amino-2- cycloheptenylphosphonate; and

di(2-chloropropyl) l-(2-hydroxyethyl)aminocyclooctylphosphonate, respectively.

EXAMPLE 4 Similarly, using the procedure described in Example 1. but replacing the di(2-chloropropyl)phosphite there employed by an equivalent amount of di(tri- 'chloromethyl) phosphite. di-n-hexyl phosphite. diallyl phosphite. di(p-chlorophenyl) phosphite, dibenzyl phosphite or dichlorohexyl phosphite, there was obtained:

di(trichloromet'hyl),

EXAMPLE 6 The following experiment was carried out to compare the relative rates of reactivity of the two active hyphosphonate drogen atoms in di( 2-chloropropyl) l-(2-hydroxyethyl- )aminocyclohexyl phosphonate (prepared as described in Example I) and the previously known di(2- chloropropyl) 2-( 2-hydroxyethyl )amino-Zpropyl- [prepared from di(2- chloropropyl)phosphite, acetone and ethanolamine using the procedure described in Example 1].

A solution of 3.5 g. (0.0093 mole) of di(2- chloropropyl) l-( Z-hydroxye-thyl )aminocyclohexylphosphonate in 50 ml. of anhydrous benzene was adchloropropyl) 2- (2-hydroxyethyl)amino-2- propylphosphonate in 50 ml. of anhydrous benzene, to which was added, 1 ml. of phenyl isocyanate, it was found that the absorption .band corresponding to isocyanato disappeared within a very short period (30 minutes) and a very strong band at 6.0 ,u (urea) appeared within the same time period. Even after 6 hours of reaction there was no detectable band at 5.8 ,u (urethane). However, when a second 1 ml. portion of phenylisocyanate was added the absorption band at 5.8

attached to nitrogen had reacted i.e. after 1 molar pro-- portion of isocyanate had been used and a second such portion added, did any reaction occur at the active hydrogen atom attached to oxygen.-

EXAMPLE 7 Rigid polyurethane foams were prepared using a standard formulation in-which 25 percent by weight of the polyol component was replaced bythe compound of Example 1, and, for comparison purposes, by the compound diethyl di(2-hydroxyethyl)aminornethanephosphonate [Fyrol 6]. Theformulations (all parts by weight) and physical properties of the two foams are recorded in Table 1. in both cases the polyols, surfactant, catalyst and water were blended, the freon was added, and finally the polyisocyanate was admixed with high speed stirring for 15 seconds. The resulting mixture was allowed to foam freely in a paper cup and the foam so obtained wascured in air at room temperature (circa 20C) for 3 days.

It willbe seen that the foam (Foam A) prepared using the phosphorus containing diol of Example 1 had superior physical strength properties and markedly less shrinkage on humid aging thandid the foam (Foam B) prepared from. the known phosphorus compound.

Freon (11B) TABLE l-Continued Foam A Foam B PROPERTIES Density, pcf. 2 5 2.92 Compressive strength psi 0 rise 58.8 27.0 perpendicular to rise 27.8 17.8 volume change on humid age at 158F and humidity 1 day 2.6 9 3 days 4.6 14.2 7 days 6.4 l 1.0 i 14ldays h d 9.3 11.1 a v0 ume c angc on in at 200 g V 1 day 0 0.6 7 days 2.0 2.5

propoxylating a polymcthylcnc polyphcnyl 50% diaminc and (ii) the adduct of glycerol Blend of (i) polyol obtained by polyamine containing approximately and propylene oxide (cg wt. 89). Organosiliconc DC-193.

We claim: 1. A compound having the formula:

an OH wherein R and R are each selected from the class consisting of hydrocarbyl from 1 to 12 carbon atoms, inclusive, and halo-substituted hydrocarbyl from IV tov 12 carbon atoms, inclusive;

C,,H2" represents alkylene from 2 to 8 carbon atoms,

' inclusive, having at least 2 carbon atoms separating the valencies; and

R and R taken together with the carbon atom to which they are attached, represent the residue of a cyclic member selected from the class consisting of a cycloalkane, a cycloalkene and a cycloalkanone each of said cycloalkane, cycloalkene and cycloalkanone having from 4 to 8 ring carbon atoms,

inclusive, and having from 0 to 4 low'er-alkyl substituents.

2. A compound according to claim 1 wherein R and R each represent ethyl, C,,H is CH CH and R and R taken together with the carbon atom to which they are attached represent the residue of cyclohexane, said compound being diethyl 1-( 2- hydroxyethyl)aminocyclohexylphosphonate.

3. A compound according to claim 1 wherein R, and R each represent 2-chloropropyl, C,,h is -CH C- H and R and R taken together with the carbon atom to which they are attached represent the residue of cyclohexane, said compound being di(2- chloropropyl) l-(2-hydroxyethyl)aminocyclohcxylphosphonate.

Patent No. 3,855, 363 Dated December 17, 1974 Inventor) Curtis P. Smith and Henri Ulri h It: is certified that error-appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line 26: Should read:

2cyc lohexyl 2-cyclohexenyl- Column 10 Claim 3, line 54: Should read:

n zn Q n Qn Signed and sealed this 4th day of March 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON j Commissioner'of Patents Attesting Officer 4 1 and Trademarks FORM po'wso (0459) uscoMM-oc scam-ps9 ,5. GOVERNMENT PRINTING OFFICE Z 963 O365-33 

1. A COMPOUND HAVING THE FORMULA:
 2. A compound according to claim 1 wherein R1 and R2 each represent ethyl, CnH2n is -CH2CH2- and R3 and R4 taken together with the carbon atom to which they are attached represent the residue of cyclohexane, said compound being diethyl 1-(2-hydroxyethyl)aminocyclohexylphosphonate.
 3. A compound according to claim 1 wherein R1 and R2 each represent 2-chloropropyl, Cnh2n is -CH2CH2- and R3 and R4 taken together with the carbon atom to which they are attached represent the residue of cyclohexane, said compound being di(2-chloropropyl) 1-(2-hydroxyethyl)aminocyclohexylphosphonate. 